• Energy Research

Abstract The performance of a slurry bubble column reactor was evaluated for its application as a methanation reactor. The influences of the reactor pressure (5 to 20 bar), temperature (275 to 325 °C), gas velocity (0.8 to 1.6 cm/s), catalyst concentration (1.6 to 9 vol.%) as well as reactant partial pressures (H2/CO2 ratio from 3.8 to 6.3) on the reactor performance were assessed and optimal process conditions for substitute natural gas production were identified. An increase in pressure, temperature, and H2/CO2 ratio improves the reactor performance. The optimal catalyst concentration depends on the operating conditions. Under the experimental conditions of the work presented in this paper, a concentration of 6.5 vol.% led to the highest conversion rates. Additionally, the dynamic behavior of the three-phase methanation reactor was investigated using inlet gas velocity step changes to simulate load variation of a power-to-gas facility. The reactor showed rapid adaptation while maintaining an isothermal temperature profile.

Abstract The performance of a slurry bubble column reactor was evaluated for its application as a methanation reactor. The influences of the reactor pressure (5 to 20 bar), temperature (275 to 325 °C), gas velocity (0.8 to 1.6 cm/s), catalyst concentration (1.6 to 9 vol.%) as well as reactant partial pressures (H2/CO2 ratio from 3.8 to 6.3) on the reactor performance were assessed and optimal process conditions for substitute natural gas production were identified. An increase in pressure, temperature, and H2/CO2 ratio improves the reactor performance. The optimal catalyst concentration depends on the operating conditions. Under the experimental conditions of the work presented in this paper, a concentration of 6.5 vol.% led to the highest conversion rates. Additionally, the dynamic behavior of the three-phase methanation reactor was investigated using inlet gas velocity step changes to simulate load variation of a power-to-gas facility. The reactor showed rapid adaptation while maintaining an isothermal temperature profile.

Biofuels of the second generation can contribute significantly to the replacement of the currently used fossil energy carriers for transportation fuel production. The lignocellulosic biomass residues used do not compete with food and feed production, but have to be collected from wide‐spread areas for industrial large‐scale use. The two‐stage gasification concept bioliq offers a solution to this problem. It aims at the conversion of low‐grade residual biomass from agriculture and forestry into synthetic fuels and chemicals. Central element of the bioliq process development is the 2–5 MW pilot plant along the complete process chain: fast pyrolysis for pretreatment of biomass to obtain an energy dense, liquid intermediate fuel, high‐pressure entrained flow gasification providing low methane synthesis gas free of tar, hot synthesis gas cleaning to separate acid gases, and contaminants as well as methanol/dimethyl ether and subsequent following gasoline synthesis. After construction and commissioning of the individual process steps with partners from industry, first production of synthetic fuel was successfully achieved in 2014. In addition to pilot plant operation for technology demonstration, a research and development network has been established providing the scientific basis for optimization and further development of the bioliq process as well as to explore new applications of the technologies and products involved. WIREs Energy Environ 2017, 6:e236. doi: 10.1002/wene.236This article is categorized under: Bioenergy > Science and Materials Bioenergy > Systems and Infrastructure

Biofuels of the second generation can contribute significantly to the replacement of the currently used fossil energy carriers for transportation fuel production. The lignocellulosic biomass residues used do not compete with food and feed production, but have to be collected from wide‐spread areas for industrial large‐scale use. The two‐stage gasification concept bioliq offers a solution to this problem. It aims at the conversion of low‐grade residual biomass from agriculture and forestry into synthetic fuels and chemicals. Central element of the bioliq process development is the 2–5 MW pilot plant along the complete process chain: fast pyrolysis for pretreatment of biomass to obtain an energy dense, liquid intermediate fuel, high‐pressure entrained flow gasification providing low methane synthesis gas free of tar, hot synthesis gas cleaning to separate acid gases, and contaminants as well as methanol/dimethyl ether and subsequent following gasoline synthesis. After construction and commissioning of the individual process steps with partners from industry, first production of synthetic fuel was successfully achieved in 2014. In addition to pilot plant operation for technology demonstration, a research and development network has been established providing the scientific basis for optimization and further development of the bioliq process as well as to explore new applications of the technologies and products involved. WIREs Energy Environ 2017, 6:e236. doi: 10.1002/wene.236This article is categorized under: Bioenergy > Science and Materials Bioenergy > Systems and Infrastructure

Reliable devolatilisation kinetics of primary wood chars are essential to describe the secondary of volatiles in entrained flow gasification processes but have not been derived yet. Therefore, this study developed devolatilisation kinetics of a commercially available beech wood char using ermogravimetric analyses and drop-tube reactor experiments for design of entrained flow gasification processes. The thermogravimetric analyses were performed at low heating rates (2∕5∕10∕30∕50 K∕min) up to 1273 K, whereas the drop-tube reactor experiments were conducted at high heating rates (∼ 10$^4$ K∕s), high temperatures (1273/1373/1473/1573/1673/1873 K) and short residence times (200/400 ms). Thermogravimetric kinetics were subsequently obtained based on multi first-order reaction logistic distributed activation energy models, while kinetics based on single first-order reaction Arrhenius law and modified Yamamoto models were derived from the drop-tube reactor experiments and corresponding CFD predictions. Finally, single-particle simulations were carried out to compare the kinetics from both kind of experiments at high-heating-rate conditions. The comparisons demonstrate that the thermogravimetric kinetics are in reasonable agreement with the drop-tube reactor kinetics but provide lower devolatilisation rates. Furthermore, gas species concentrations measurements from the drop-tube reactor experiments were used to estimate an average volatiles composition. The results indicate that the volatiles composition at high-temperature conditions can likely be described using the gas species concentrations at high-temperature equilibrium conditions.

Reliable devolatilisation kinetics of primary wood chars are essential to describe the secondary of volatiles in entrained flow gasification processes but have not been derived yet. Therefore, this study developed devolatilisation kinetics of a commercially available beech wood char using ermogravimetric analyses and drop-tube reactor experiments for design of entrained flow gasification processes. The thermogravimetric analyses were performed at low heating rates (2∕5∕10∕30∕50 K∕min) up to 1273 K, whereas the drop-tube reactor experiments were conducted at high heating rates (∼ 10$^4$ K∕s), high temperatures (1273/1373/1473/1573/1673/1873 K) and short residence times (200/400 ms). Thermogravimetric kinetics were subsequently obtained based on multi first-order reaction logistic distributed activation energy models, while kinetics based on single first-order reaction Arrhenius law and modified Yamamoto models were derived from the drop-tube reactor experiments and corresponding CFD predictions. Finally, single-particle simulations were carried out to compare the kinetics from both kind of experiments at high-heating-rate conditions. The comparisons demonstrate that the thermogravimetric kinetics are in reasonable agreement with the drop-tube reactor kinetics but provide lower devolatilisation rates. Furthermore, gas species concentrations measurements from the drop-tube reactor experiments were used to estimate an average volatiles composition. The results indicate that the volatiles composition at high-temperature conditions can likely be described using the gas species concentrations at high-temperature equilibrium conditions.

AbstractFossil fuels have to be substituted by climate neutral fuels to contribute to CO2 reduction in the future energy system. Pyrolysis of natural gas is a well‐known technical process applied for production of, e. g., carbon black. In the future it might contribute to carbon dioxide‐free hydrogen production. Production of hydrogen from natural gas pyrolysis has thus gained interest in research and energy technology in the near past. If the carbon by‐product of this process can be used for material production or can be sequestrated, the produced hydrogen has a low carbon footprint. This article reviews literature on the state of the art of methane / natural gas pyrolysis process developments and attempts to assess the technology readiness level (TRL).

AbstractFossil fuels have to be substituted by climate neutral fuels to contribute to CO2 reduction in the future energy system. Pyrolysis of natural gas is a well‐known technical process applied for production of, e. g., carbon black. In the future it might contribute to carbon dioxide‐free hydrogen production. Production of hydrogen from natural gas pyrolysis has thus gained interest in research and energy technology in the near past. If the carbon by‐product of this process can be used for material production or can be sequestrated, the produced hydrogen has a low carbon footprint. This article reviews literature on the state of the art of methane / natural gas pyrolysis process developments and attempts to assess the technology readiness level (TRL).